Ultrabarrier substrates

ABSTRACT

A barrier assembly. The barrier assembly includes at least one barrier stack having at least one barrier layer and at least one polymer layer. The barrier stack has an oxygen transmission rate of less than 0.005 cc/m 2 /day at 23° C. and 0% relative humidity, and an oxygen transmission rate of less than 0.005 cc/m 2 /day at 38° C. and 90% relative humidity. The barrier stack also has a water vapor transmission rate of less than 0.005 g/m 2 /day at 38° C. and 100% relative humidity. A method for making a barrier assembly is also disclosed.

This application is a continuation-in-part of U.S. patent applicationSer. No. 09/427,138, filed Oct. 25, 1999, entitled “EnvironmentalBarrier Material For Organic Light Emitting Device and Method OfMaking,” now U.S. Pat. No. 6,522,067, issued Feb. 18, 2003.

BACKGROUND OF THE INVENTION

The present invention relates generally to barrier coatings, and moreparticularly to barrier coatings having improved barrier properties.

Many different types of products are sensitive to gas and liquids, whichcan cause deterioration of the product or render it useless, includingelectronics, medical devices, and pharmaceuticals. Barrier coatings havebeen included in the packaging for these environmentally sensitiveproducts to protect them from gas and liquid transmission. As usedherein, the term environmentally sensitive means products which aresubject to degradation caused by permeation of environmental gases orliquids, such as oxygen and water vapor in the atmosphere or chemicalsused in the processing, handling, storage, and use of the product.

Plastics are often used in product packaging. However, the gas andliquid permeation resistance of plastics is poor, often several ordersof magnitude below what is required for product performance. Forexample, the oxygen transmission rates for materials such polyethyleneterephthalate (PET) are as high as 1550 cc/m²/day/micron of thickness(or 8.7 cc/m²/day for 7 mil thickness PET), and the water vaportransmission rates are also in this range. Certain display applicationsusing environmentally sensitive display devices, such as organic lightemitting devices, require encapsulation that has a maximum oxygentransmission rate of 10⁻⁴ to 10⁻² cc/m²/day, and a maximum water vaportransmission rate of 10⁻⁵ to 10⁻⁶ g/m²/day.

Barrier coatings have been applied to plastic substrates to decreasetheir gas and liquid permeability. Barrier coatings typically consist ofsingle layer thin film inorganic materials, such as Al, SiO_(x),AlO_(x), an Si₃N₄ vacuum deposited on polymeric substrates. A singlelayer coating on PET reduces oxygen permeability to levels of about 0.1to 1.0 cc/m²/day, and water vapor permeability to about 0.1 to 1.0g/m²/day, which is insufficient for many display devices.

Barrier coatings which include alternating barrier layers and polymericlayers have been developed. For example, U.S. Pat. Nos. 5,607,789 and5,681,666 disclose a moisture barrier for an electrochemical celltester. However, the claimed moisture barrier ranges from 2 to 15micrograms/in²/day which corresponds to a rate of 0.003 to 0.023g/m²/day. U.S. Pat. No. 5,725,909 to Shaw et al. discloses a coating forpackaging materials which has an acrylate layer and an oxygen barrierlayer. The oxygen transmission rate for the coating was reported to be0.1 cc/m²/day at 23° C. and the water vapor transmission rate wasreported to be 0.01 g/m²/day in D. G. Shaw and M. G. Langlois, Societyof Vacuum Coaters, 37^(th) Annual Technical Conference Proceedings, p.240-244, 1994. The oxygen transmission rates for these coatings areinadequate for many display devices.

Thus, there is a need for an improved, lightweight, barrier coating, andfor methods for making such a barrier coating.

SUMMARY OF THE INVENTION

The present invention meets these needs by providing a barrier assemblyand a method for making such an assembly. The barrier assembly includesat least one barrier stack having at least one barrier layer and atleast one polymer layer. The barrier stack has an oxygen transmissionrate of less than 0.005 cc/m²/day at 23° C. and 0% relative humidity,and an oxygen transmission rate of less than 0.005 cc/m²/day at 38° C.and 90% relative humidity. It also preferably has a water vaportransmission rate of less than 0.005 g/m^(2/)day at 38° C. and 100%relative humidity.

Preferably, the barrier layers of the barrier stacks are substantiallytransparent. At least one of the barrier layers preferably comprises amaterial selected from metal oxides, metal nitrides, metal carbides,metal oxynitrides, metal oxyborides, and combinations thereof.

The barrier layers can be substantially opaque, if desired. The opaquebarrier layers are preferably selected from opaque metals, opaquepolymers, and opaque ceramics.

The barrier assembly can include a substrate adjacent to the at leastone barrier stack. By adjacent, we mean next to, but not necessarilydirectly next to. There can be additional layers intervening between theadjacent layers. The substrate can either be flexible or rigid. It ispreferably made of a flexible substrate material, such as polymers,metals, paper, fabric, and combinations thereof. If a rigid substrate isused, it is preferably a ceramic (including glasses), a metal, or asemiconductor.

The polymer layers of the barrier stacks are preferablyacrylate-containing polymers. As used herein, the termacrylate-containing polymers includes acrylate-containing polymers,methacrylate-containing polymers, and combinations thereof The polymerlayers can be the same or different.

The barrier assembly can include additional layers if desired, such aspolymer smoothing layers, scratch resistant layers, antireflectivecoatings, or other functional layers.

The present invention also involves a method of making the barrierassembly. The method includes providing a substrate, and placing atleast one barrier stack on the substrate. The barrier stack includes atleast one barrier layer and at least one polymer layer.

The at least one barrier stack can be placed on the substrate bydeposition, preferably vacuum deposition, or by laminating the barrierstack over the environmentally sensitive device. The lamination can beperformed using an adhesive, solder, ultrasonic welding, pressure, orheat.

Accordingly, it is an object of the present invention to provide abarrier assembly, and to provide a method of making such a barrierassembly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-section of one embodiment of the barrier assembly ofthe present invention.

FIG. 2 is a cross-section of an encapsulated device made using thebarrier assembly of the present invention.

DESCRIPTION OF THE INVENTION

One embodiment of the barrier assembly of the present invention is shownin FIG. 1. The barrier assembly is supported by a substrate 105. Thesubstrate 105 can be either rigid or flexible. A flexible substrate canbe any flexible material, including, but not limited to: polymers, forexample, polyethylene terephthalate (PET), polyethylene naphthalate(PEN), or high temperature polymers, such as polyether sulfone (PES),polyimides, or Transphan™ (a high glass transition temperature cyclicolefin polymer available from Lofo High Tech Film, GMBH or Weil amRhein, Germany); metal; paper; fabric; and combinations thereof. Rigidsubstrates are preferably glass, metal, or silicon.

There are scratch resistant layers 110 on either side of the substrate105 to protect it. When a scratch resistant layer is included, it ispreferred that both sides of the substrate have a scratch resistantlayer. This helps to balance stresses and prevent deformation of aflexible substrate during processing and use.

On top of the scratch resistant layer 110, there is a polymer smoothinglayer 115. The polymer smoothing layer decreases surface roughness, andencapsulates surface defects, such as pits, scratches, and digs. Thisproduces a planarized surface which is ideal for subsequent depositionof layers. Depending on the desired application, there can be additionallayers deposited on the substrate 105, such as organic or inorganiclayers, planarizing layers, electrode layers, antireflective coatings,and other functional layers. In this way, the substrate can bespecifically tailored to different applications.

The first barrier stack 120 is adjacent to the polymer smoothing layer115. The first barrier stack 120 includes a barrier layer 125 and apolymer layer 130. The first barrier layer 125 includes barrier layers135 and 140. Barrier layers 135 and 140 can be made of the same barriermaterial or of different barrier materials.

Although FIG. 1 shows a barrier stack with two barrier layers and onepolymer layer, the barrier stacks can have one or more polymer layersand one or more barrier layers. There could be one polymer layer and onebarrier layer, there could be one or more polymer layers on one side ofone or more barrier layers, or there could be one or more polymer layerson both sides of one or more barrier layers. The important feature isthat the barrier stack have at least one polymer layer and at least onebarrier layer. The barrier layers and polymer layers in the barrierstack can be made of the same material or of a different material. Thebarrier layers are typically about 100-400 Å thick, and the polymerlayers are typically about 1000-10,000 Å thick.

Although only one barrier stack is shown in FIG. 1, the number ofbarrier stacks is not limited. The number of barrier stacks neededdepends on the substrate material used and the level of permeationresistance needed for the particular application. One or two barrierstacks should provide sufficient barrier properties for someapplications. The most stringent applications may require five or morebarrier stacks.

There is a transparent conductor 145, such as an indium tin oxide layer,adjacent to the first barrier stack 120. There can be additionalovercoat layers on top of the barrier stack, such as organic orinorganic layers, planarizing layers, transparent conductors,antireflective coatings, or other functional layers, if desired. Thisallows the barrier assembly to be tailored to the application.

FIG. 2 shows a barrier assembly being used to encapsulate anenvironmentally sensitive display device. The substrate 205 has anenvironmentally sensitive display device 210 on it. There is a barrierstack 215 over the environmentally sensitive display device 210encapsulating it. The barrier stack 215 includes a barrier layer 220 anda polymer layer 225.

The environmentally sensitive display device 210 can be any displaydevice which is environmentally sensitive. Examples of environmentallysensitive display devices include, but are not limited to liquid crystaldisplays (LCDs), light emitting diodes (LEDs), light emitting polymers(LEPs), electronic signage using electrophoretic inks,electroluminescent devices (EDs), and phosphorescent devices. Thesedisplay devices can be made using known techniques, such as thosedescribed in U.S. Pat. Nos. 6,025,899, 5,995,191, 5,994,174, 5,956,112(LCDs); U.S. Pat. Nos. 6,005,692, 5,821,688, 5,747,928 (LEDs); U.S. Pat.Nos. 5,969,711, 5,961,804, 4,026,713 (E Ink); U.S. Pat. Nos. 6,023,373,6,023,124, 6,023,125 (LEPs); and U.S. Pat. Nos. 6,023,073, 6,040,812,6,019,654, 6,018,237, 6,014,119, 6,010,796 (EDs), which are incorporatedherein by reference.

The method of making the barrier assembly will be described withreference to FIGS. 1 and 2. Any initial layers which are desired, suchas scratch resistant layers, planarizing layers, electrically conductivelayers, etc., can be coated, deposited, or otherwise placed on thesubstrate. A polymer smoothing layer is preferably included to provide asmooth base for the remaining layers. It can be formed by depositing alayer of polymer, for example, an acrylate-containing polymer, onto thesubstrate or previous layer. The polymer layer can be deposited invacuum or by using atmospheric processes such as spin coating and/orspraying. Preferably, an acrylate-containing monomer, oligomer, or resinis deposited and then polymerized in situ to form the polymer layer. Asused herein, the term acrylate-containing monomer, oligomer, or resinincludes acrylate-containing monomers, oligomers, and resins,methacrylate-containing monomers, oligomers, and resins, andcombinations thereof.

The barrier stack is then placed on the substrate. The barrier stackincludes at least one barrier layer and at least one polymer layer. Thebarrier stacks are preferably made by vacuum deposition. The barrierlayer can be vacuum deposited onto the polymer smoothing layer, thesubstrate, or the previous layer. The polymer layer is then deposited onthe barrier layer, preferably by flash evaporating acrylate-containingmonomers, oligomers, or resins, condensing on the barrier layer, andpolymerizing in situ in a vacuum chamber. U.S. Pat. Nos. 5,440,446 and5,725,909, which are incorporated herein by reference, describe methodsof depositing thin film, barrier stacks.

Vacuum deposition includes flash evaporation of acrylate-containingmonomer, oligomer, or resin with in situ polymerization under vacuum,plasma deposition and polymerization of acrylate-containing monomer,oligomer, or resin, as well as vacuum deposition of the barrier layersby sputtering, chemical vapor deposition, plasma enhanced chemical vapordeposition, evaporation, sublimation, electron cyclotronresonance-plasma enhanced vapor deposition (ECR-PECVD), and combinationsthereof.

In order to protect the integrity of the barrier layer, the formation ofdefects and/or microcracks in the deposited layer subsequent todeposition and prior to downstream processing should be avoided. Thebarrier assembly is preferably manufactured so that the barrier layersare not directly contacted by any equipment, such as rollers in a webcoating system, to avoid defects that may be caused by abrasion over aroll or roller. This can be accomplished by designing the depositionsystem such that the barrier layers are always covered by polymer layersprior to contacting or touching any handling equipment.

When the barrier stack is being used to encapsulate an environmentallysensitive display device, the substrate can be prepared as describedabove, and the environmentally sensitive display device placed on thesubstrate. Alternatively, the environmentally sensitive display devicecan be placed directly on a substrate (or on a substrate with functionallayers, such as planarizing layers, scratch resistant layers, etc.).

The environmentally sensitive display device can be placed on thesubstrate by deposition, such as vacuum deposition. Alternatively it canbe placed on the substrate by lamination. The lamination can use anadhesive, glue, or the like, or heat to seal the environmentallysensitive display device to the substrate.

A barrier stack is then placed over the environmentally sensitivedisplay device to encapsulate it. The second barrier stack can be placedover the environmentally sensitive display device by deposition orlamination.

The barrier layers in the first and second barrier stacks may be anybarrier material. The barrier layers in the first and second barrierstacks can be made of the same material or a different material. Inaddition, multiple barrier layers of the same or different barriermaterials can be used in a barrier stack.

The barrier layers can be transparent or opaque, depending on the designof the packaging, and application for which it is to be used. Preferredtransparent barrier materials include, but are not limited to, metaloxides, metal nitrides, metal carbides, metal oxynitrides, metaloxyborides, and combinations thereof. The metal oxides are preferablyselected from silicon oxide, aluminum oxide, titanium oxide, indiumoxide, tin oxide, indium tin oxide, tantalum oxide, zirconium oxide,niobium oxide, and combinations thereof. The metal nitrides arepreferably selected from aluminum nitride, silicon nitride, boronnitride, and combinations thereof. The metal oxynitrides are preferablyselected from aluminum oxynitride, silicon oxynitride, boron oxynitride,and combinations thereof.

Opaque barrier layers can be also be used in some barrier stacks. Opaquebarrier materials include, but are not limited to, metals, ceramics,polymers, and cermets. Examples of opaque cermets include, but are notlimited to, zirconium nitride, titanium nitride, hafnium nitride,tantalum nitride, niobium nitride, tungsten disilicide, titaniumdiboride, and zirconium diboride.

The polymer layers of the first and second barrier stacks are preferablyacrylate-containing monomers, oligomers, or resins. The polymer layersin the first and second barrier stacks can be the same or different. Inaddition, the polymer layers within each barrier stack can be the sameor different.

In a preferred embodiment, the barrier stack includes a polymer layerand two barrier layers. The two barrier layers can be made from the samebarrier material or from different barrier materials. The thickness ofeach barrier layer in this embodiment is about one half the thickness ofthe single barrier layer, or about 50 to 200 Å. There are no limitationson the thickness, however.

When the barrier layers are made of the same material, they can bedeposited either by sequential deposition using two sources or by thesame source using two passes. If two deposition sources are used,deposition conditions can be different for each source, leading todifferences in microstructure and defect dimensions. Any type ofdeposition source can be used. Different types of deposition processes,such as magnetron sputtering and electron beam evaporation, can be usedto deposit the two barrier layers.

The microstructures of the two barrier layers are mismatched as a resultof the differing deposition sources/parameters. The barrier layers caneven have different crystal structure. For example, Al₂O₃ can exist indifferent phases (alpha, gamma) with different crystal orientations. Themismatched microstructure can help decouple defects in the adjacentbarrier layers, enhancing the tortuous path for gases and water vaporpermeation.

When the barrier layers are made of different materials, two depositionsources are needed. This can be accomplished by a variety of techniques.For example, if the materials are deposited by sputtering, sputteringtargets of different compositions could be used to obtain thin films ofdifferent compositions. Alternatively, two sputtering targets of thesame composition could be used but with different reactive gases. Twodifferent types of deposition sources could also be used. In thisarrangement, the lattices of the two layers are even more mismatched bythe different microstructures and lattice parameters of the twomaterials.

A single pass, roll-to-roll, vacuum deposition of a three layercombination on a PET substrate, i.e., PET substrate/polymerlayer/barrier layer/polymer layer, can be more than five orders ofmagnitude less permeable to oxygen and water vapor than a single oxidelayer on PET alone. See J. D. Afinito, M. E. Gross, C. A. Coronado, G.L. Graff, E. N. Greenwell, and P. M. Martin, Polymer-Oxide TransparentBarrier Layers Produced Using PML Process, 39^(th) Annual TechnicalConference Proceedings of the Society of Vacuum Coaters, Vacuum WebCoating Session, 1996, pages 392-397; J. D. Affinito, S. Eufinger, M. E.Gross, G. L. Graff, and P. M. Martin, PML/Oxide/PML Barrier LayerPerformance Difference Arising From Use of UV or Electron BeamPolymerization of the PML Layers, Thin Solid Films, Vol. 308, 1997,pages 19-25. This is in spite of the fact that the effect on thepermeation rate of the polymer multilayers (PML) layers alone, withoutthe barrier layer (oxide, metal, nitride, oxynitride) layer, is barelymeasurable. It is believed that the improvement in barrier properties isdue to two factors. First, permeation rates in the roll-to-roll coatedoxide-only layers were found to be conductance limited by defects in theoxide layer that arose during deposition and when the coated substratewas wound up over system idlers/rollers. Asperities (high points) in theunderlying substrate are replicated in the deposited inorganic barrierlayer. These features are subject to mechanical damage during webhandling/take-up, and can lead to the formation of defects in thedeposited film. These defects seriously limit the ultimate barrierperformance of the films. In the single pass, polymer/barrier/polymerprocess, the first acrylic layer planarizes the substrate and providesan ideal surface for subsequent deposition of the inorganic barrier thinfilm. The second polymer layer provides a robust “protective” film thatminimizes damage to the barrier layer and also planarizes the structurefor subsequent barrier layer (or environmentally sensitive displaydevice) deposition. The intermediate polymer layers also decoupledefects that exist in adjacent inorganic barrier layers, thus creating atortuous path for gas diffusion.

The permeability of the barrier stacks used in the present invention isshown in Table 1. The barrier stacks of the present invention onpolymeric substrates, such as PET, have measured oxygen transmissionrate (OTR) and water vapor transmission rate (WVTR) values well belowthe detection limits of current industrial instrumentation used forpermeation measurements (Mocon OxTran 2/20L and Permatran). Table 1shows the OTR and WVTR values (measured according to ASTM F 1927-98 andASTM F 1249-90, respectively) measured at Mocon (Minneapolis, Minn.) forseveral barrier stacks on 7 mil PET, along with reported values forother materials.

TABLE 1 Oxygen Water Vapor Permeation Rate Permeation (cc/m²/day)(g/m²/day)* Sample 23° C. 38° C. 23° C. 38° C. Native 7 mil PET 7.62 — —— 1-barrier stack <0.005 <0.005* — 0.46* 1-barrier stack <0.005 <0.005*— 0.011* with ITO 2-barrier stacks <0.005 <0.005* — <0.005* 2-barrierstacks <0.005 <0.005* — <0.005* with ITO 5-barrier stacks <0.005 <0.005*— <0.005* 5-barrier stacks <0.005 <0.005* — <0.005* with ITO DuPontfilm¹ 0.3 — — — (PET/Si₃N₄ or PEN/Si₃N₄) Polaroid³ <1.0 — — — PET/Al²0.6 — 0.17 — PET/silicon 0.7-1.5 — 0.15-0.9 — oxide² Teijin LCD film <2— <5 — (HA grade- TN/STN)³ *38° C., 90% RH, 100% O₂ *38° C., 100% RH ¹P.F. Carcia, 46^(th) International Symposium of the American VacuumSociety, October 1999 ²Langowski, H. C., 39^(th) Annual TechnicalConference Proceedings, SVC, pp. 398-401 (1996) ³Technical Data Sheet

As the data in Table 1 shows, the barrier stacks of the presentinvention provide oxygen and water vapor permeation rates several ordersof magnitude better than PET coated with aluminum, silicon oxide, oraluminum oxide. Typical oxygen permeation rates for other barriercoatings range from 1 to about 0.1 cc/m²/day. The oxygen transmissionrate for the barrier stacks of the present invention is less than 0.005cc/m²/day at 23° C. and 0% relative humidity, and at 38° C. and 90%relative humidity. The water vapor transmission rate is less than 0.005g/m²/day at 38° C. and 100% relative humidity. The actual transmissionrates are lower, but cannot be measured with existing equipment.

The barrier assemblies were also tested by encapsulating organic lightemitting devices using the barrier stacks of the present invention. Theorganic light emitting devices are extremely sensitive to water vapor,and they are completely destroyed in the presence of micromolequantities of water vapor. Experimentation and calculations suggest thatthe water vapor transmission rate through the encapsulation film must beon the order of about 10⁻⁶ to 10⁻⁵ g/m²/day to provide sufficientbarrier protection for acceptable device lifetimes. Theexperiments/calculations are based on the detrimental hydrolysisreaction of water vapor with the extremely thin (less than 10 nm), lowwork function, cathode materials (Ca, Mg, Li, LiF). Hydrolysis of thecathode leads to the formation of non-conductive reaction products (suchas hydroxides and oxides) that delaminate or blister away from theelectron transport layers of the organic light emitting devices,resulting in the formation of dark spots on the device.

The organic light emitting devices encapsulated in the barrier stacks ofthe present invention have been in operation for over six months andwithout measurable degradation. The extrapolated lifetime for theencapsulated devices exceeds the required 10,000 hours necessary tosatisfy industry standards. The barrier stacks are extremely effectivein preventing oxygen and water penetration to the underlying components,substantially outperforming other thin-film barrier coatings on themarket.

The preferred deposition process is compatible with a wide variety ofsubstrates. Because the preferred process involves flash evaporation ofa monomer and magnetron sputtering, deposition temperatures are wellbelow 100° C., and stresses in the coating can be minimized. Multilayercoatings can be deposited at high deposition rates. No harsh gases orchemicals are used, and the process can be scaled up to large substratesand wide webs. The barrier properties of the coating can be tailored tothe application by controlling the number of layers, the materials, andthe layer design. Thus, the present invention provides a barrier stackwith the exceptional barrier properties necessary for hermetic sealingof an environmentally sensitive display device, or other environmentallysensitive device. It permits the production of an encapsulatedenvironmentally sensitive display device.

While certain representative embodiments and details have been shown forpurposes of illustrating the invention, it will be apparent to thoseskilled in the art that various changes in the compositions and methodsdisclosed herein may be made without departing from the scope of theinvention, which is defined in the appended claims.

1. A barrier assembly comprising: at least one barrier stack comprisingat least one barrier layer and at least one polymer layer, wherein theat least one barrier stack has an oxygen transmission rate of less than0.005 cc/m²/day at 23° C. and 0% relative humidity.
 2. The barrierassembly of claim 1 wherein the at least one barrier stack has an oxygentransmission rate of less than 0.005 cc/m²/day at 38° C. and 90%relative humidity.
 3. The barrier assembly of claim 1 wherein the atleast one barrier stack has a water vapor transmission rate of less than0.005 g/m²/day at 38° C. and 100% relative humidity.
 4. The barrierassembly of claim 1 further comprising a substrate adjacent to the atleast one barrier stack.
 5. The barrier assembly of claim 1 wherein theat least one barrier layer is substantially transparent.
 6. The barrierassembly of claim 1 wherein at least one of the at least one barrierlayer comprises a material selected from metal oxides, metal nitrides,metal carbides, metal oxynitrides, metal oxyborides, and combinationsthereof.
 7. The barrier assembly of claim 6 wherein the metal oxides areselected from silicon oxide, aluminum oxide, titanium oxide, indiumoxide, tin oxide, indium tin oxide, tantalum oxide, zirconium oxide,niobium oxide, and combinations thereof.
 8. The barrier assembly ofclaim 6 wherein the metal nitrides are selected from aluminum nitride,silicon nitride, boron nitride, and combinations thereof.
 9. The barrierassembly of claim 6 wherein the metal oxynitrides are selected fromaluminum oxynitride, silicon oxynitride, boron oxynitride, andcombinations thereof.
 10. The barrier assembly of claim 1 wherein the atleast one barrier layer is substantially opaque.
 11. The barrierassembly of claim 1 wherein at least one of the at least one barrierlayers is selected from opaque metals, opaque polymers, opaque ceramics,and opaque cermets.
 12. The barrier assembly of claim 4 wherein thesubstrate comprises a flexible substrate material.
 13. The barrierassembly of claim 12 wherein the flexible substrate material is selectedfrom polymers, metals, paper, fabric, and combinations thereof.
 14. Thebarrier assembly of claim 4 wherein the substrate comprises a rigidsubstrate material.
 15. The barrier assembly of claim 14 wherein therigid substrate material is selected from ceramics, metals, andsemiconductors.
 16. The barrier assembly of claim 1 wherein at least oneof the at least one polymer layers comprises an acrylate-containingpolymer.
 17. The barrier assembly of claim 4 further comprising apolymer smoothing layer adjacent to the substrate.
 18. The barrierassembly of claim 4 further comprising a scratch resistant layeradjacent to the substrate.
 19. The barrier assembly of claim 4 furthercomprising an anti-reflective coating adjacent to the substrate.
 20. Thebarrier assembly of claim 4 further comprising an anti-fingerprintcoating adjacent to the substrate.
 21. The barrier assembly of claim 4further comprising an anti-static coating adjacent to the substrate. 22.The barrier assembly of claim 1 wherein the at least one barrier layercomprises two barrier layers.
 23. The barrier assembly of claim 22wherein the two barrier layers are made of the same barrier material.24. The barrier assembly of claim 22 wherein the two barrier layers aremade of different barrier materials.
 25. The barrier assembly of claim11 wherein at least one of the at least one barrier layers is opaquecermet selected from zirconium nitride, titanium nitride, hafniumnitride, tantalum nitride, niobium nitride, tungsten disilicide,titanium diboride, and zirconium diboride.